The present invention relates to a seal for use with a medical device such as a catheter and introducer needle assembly. Although this invention has particular applicability to a catheter and introducer needle assembly, it is to be understood that the seal of this invention may be used in connection with other devices requiring a fluid seal as well.
Catheters, particularly intravenous (IV) catheters, are used for directing fluid into or withdrawing fluid from a patient. The most common type of IV catheter is an over the needle catheter. As its name implies, an over the needle catheter is mounted over an introducer needle having a sharp distal tip. With the distal tip of the introducer needle extending beyond the distal tip of the catheter, the assembly is inserted through the patient's skin into a blood vessel. Once placement of the assembly in the blood vessel is verified by flashback of blood in the needle and into a flashback chamber located at the proximal end of the needle, the needle is withdrawn leaving the catheter in place.
In standard catheters, the proximal end of the catheter typically has a hub, through which the introducer needle extends, that is designed to be connectable to a fluid supply line after insertion of the catheter in a patient and removal of the introducer needle. When the introducer needle is removed from the catheter and before the fluid supply line is connected to the catheter hub, there is nothing blocking the flow of fluid into or out of the patient through the catheter. And since the catheter is located in a patient's blood vessel, blood can flow out of the catheter and contaminate the clinician as well as other personnel and medical supplies that happen to be in the area. Similarly, where a catheter with a side port is used, blood can flow out of the proximal end of the catheter hub through the portion where the introducer needle was located even when a fluid supply line is connected to the side port before the introducer needle is removed.
In recent years there has been increasing need for catheters that eliminate or at least limit the amount of blood leakage therefrom. This need has arisen because of the advent of currently incurable and sometimes fatal diseases, such as hepatitis and acquired immunodeficiency syndrome ("AIDS"), which can be transmitted by the exchange of body fluids from an infected person to another person. As a result of this need, some catheters have been designed to include some type of seal in the portion of the catheter hub through which the introducer needle extends to minimize blood leakage through the catheter hub once the catheter has been properly placed in a patient's blood vessel and the introducer needle has been removed. Typical seals merely comprise an elastic plug located in the catheter hub. This allows the introducer needle to extend through the plug and to be subsequently removed from the plug once the catheter is properly in place in a blood vessel. Since the plug is elastic, the plug should reseal once the needle is removed from the seal. Unfortunately such seals in these prior devices may be inadequate.
For example, the elastic plug tends to take a set around the introducer needle during the time that the catheter and introducer needle assembly is shipped to a customer and held in inventory prior to use. This is particularly problematic where large gauge introducer needles are used. Once the introducer needle is removed, instead of the plug sealing the opening left by the needle, the opening remains in the plug. This opening provides a path for blood flow out of the catheter. In addition, such an opening provides a path for infection to enter the patient's blood stream. Moreover, such elastic plug seals are not particularly effective in preventing leakage in high pressure locations.